One of the vital signs of a person often measured is the blood pressure (BP). Though the basic procedure of measuring physiological parameters such as blood pressure may be a simple one, there are certain conditions to be met and protocols to be adhered to, just before and during the measurement to obtain dependable measurement values.
Changes in demography, ageing populations for instance, the increasing healthcare costs, expected shortage of medical staff, growing demand for improved healthcare in emerging and developing countries will drive further changes in the healthcare systems. Patients will not only be monitored sporadically in the hospitals during acute phases but also in low acuity settings and even at home, where they are often unsupervised or unassisted by trained staff. To enable this, the patients may even be asked to make reliable measurements themselves (i.e. monitoring everywhere, ubiquitous monitoring).
The published patent application US20110224500 describes a body-worn vital sign monitor that measures a patient's vital signs (e.g. blood pressure, SpO2, heart rate, respiratory rate, and temperature) while simultaneously characterizing their activity state (e.g. resting, walking, convulsing, falling) and posture (upright, supine). The monitor processes this information to minimize corruption of the vital signs and associated alarms/alerts by motion-related artifacts.
In this case, the measurements are made at whatever conditions prevail at the time of the measurements and using other physiological parameters the vital sign values are processed to reduce the artifacts.
However, there are many patients either at home or in a care facility who need not be monitored on a continuous basis but whose physiological parameters need to be measured accurately, adhering to measurement protocols, to obtain dependable readings of the physiological parameters, a few times a day. This is increasingly being done by the patient himself/herself. (In the text here after, the masculine pronoun will be used for clarity though both masculine and feminine are implicitly intended) In such cases, however, it has to be ensured that the patient measures his own physiological parameters under proper and well-defined conditions that would make the measured physiological parameters values dependable for decisions based on them. Further, when physiological parameters values are stored for recognizing a trend in the physiological parameters, if the measured values are not dependable, as an obvious consequence, the trend also is rendered undependable.
Physiological parameters measurements done by the patient himself are prone to errors and artifacts since they are often not done according to established and standardized protocols. For example, a patient is expected to have rested for at least five minutes immediately before the start of a Blood Pressure (BP) measurement; he should not talk during the measurement; the measurements must be made when the body is in a prescribed position Ankle brachial pressure index and Pulse wave velocity are other examples of such measurements that require predefined conditions for dependable measurements. Since many patients do not comply with such requirements consistently, physiological parameter measurements are often difficult to interpret for the clinicians/physicians and are of limited value in disease management systems for decision support.
However, new monitoring and treatment concepts in unsupervised scenarios e.g. in home monitoring/tele-monitoring need accurate physiological parameter measurements as key input parameters. One example is the management of congestive heart failure patients as described in the paper “Cardiac Status Assessment with a Multi-Signal Device for Improved Home-based Congestive Heart Failure Management”, by Jens Muehlsteff et al, called “Hemodynamic Tailoring” aiming at personalized treatment and therapy using hemodynamic variables to assess the patient's health status. In general any decision support system requires reliable measurements. This concept inherently provides means to check the quality of a physiological parameter measurement. If the quality of a measurement is considered too low, the system may reject a BP measurement supplied to it as input.